body {
    margin: 4px;
    font-family: Helvetica;

    /* Centering & Limit Width */
    margin: auto;
    width: 720px;
}

.masonry {
    column-count: 4;
    column-gap: 0;
}

.item {
    padding: 2px;
    position: relative;
    counter-increment: item-counter;
}

.item img {
    display: block;
    width: 100%;
    height: auto;
}

.item::after {
    position: absolute;
    display: block;
    top: 2px;
    left: 2px;
    width: 24px;
    height: 24px;
    text-align: center;
    line-height: 24px;
    background-color: #000;
    color: #fff;
    content: counter(item-counter);
}